1. Field of the Invention
The present invention relates to gyroscopes, and in particular to an improved two-axis open loopxe2x80x9cspinning massxe2x80x9d gyroscope capable of detecting angular input rates about two orthogonal axes without the use of slip rings.
2. Description of Related Art
Prior art gyroscopes that incorporate a gyroscopic element (flywheel) and a spin motor, typically incorporate piezoelectric crystals as pickoffs. When an angular motion is applied to the gyroscope the piezoelectric crystal is bent, which provides an electrical signal as a function of the bending. The electrical signal is then conducted through wires connected to the crystal and then through shaft-mounted slip rings for use: by external circuitry. These prior art devices require added machining features, and additional mounting components, such as the slip rings. Great care must be exercised during the assembly process. Moreover, output signals from the piezoelectric crystal pickoffs are highly susceptible to slip ring contamination, thereby significantly reducing the life of the gyroscope because of the slip ring wear.
U.S Pat. No. 4,715,227 discloses a gyroscope for detecting angular rates and linear accelerations by the use of a diamond-shaped piezoelectric crystal beam. This device suffers from the problems mentioned above when using piezoelectric crystals for pickoffs.
U.S Pat. No. 5,156,056 discloses a gyroscope having two specifically restrained piezoelectric crystals aligned perpendicular to the spin axis. This prior art device has the same problems as discussed above. That is, the use of piezoelectric crystals requiring slip rings.
Therefore a need exists for an improved two-axis gyroscope capable of detecting angular input rates about two orthogonal axes without the use of slip rings.
The present invention provides a simplified low-cost solution for applications requiring a two-axis gyroscope.
The present invention also provides an open loop device not requiring electromagnetic devices that provide torque.
The present invention also provides an open loop device not requiring wire wound coils and magnets.
A feature of the present invention is the provision of a simplified two-axis open loop gyroscope that can be built from commercially available LED""s and optical detectors as rotor pickoffs, thereby eliminating the need for wire wound AC-excited coils and laminated iron cores.
An advantage of the present invention is the reduced number of component parts required to construct the gyroscope.
Another advantage of the present invention is the simplification of the electronics necessary for its operation.
Yet another advantage of the present invention is that by eliminating magnetic torquers and pickoffs, specialized magnetic steels and their associated heat treats can be replaced with lower cost rotor and housing materials, such as stainless steel.
These and other features and advantages of the present invention, which will become apparent as the invention is described in detail below. The invention is a gyroscope having a rotor mounted onto a rotating shaft. The rotor has a circular flange extending from and perpendicular to one surface thereof. A suspension member having a flexible flange is affixed concentric with the rotating shaft and the rotor. A hysteresis synchronous electric drive motor is used for spinning the combined shaft with rotor. A light source is disposed on a stationary plate for emitting light perpendicular to a surface of the circular flange of the rotor. A light sensor is also disposed on the stationary plate and on a side of the circular flange opposite of the light source for producing an electrical signal as a function of the amount of light received. The light source and the light sensor are positioned such that only a portion of the light from the source strikes the sensor when the gyro is in a quiescent rotating state. However, when the rotor is tilted as a function of an angular rotation rate applied to the gyroscope, the amount of light received by the sensor varies thereby producing an electrical signal indicative of the angular rotation rate.